Process control systems can be utilized to control process facilities such as, for example, chemical, petroleum and other industrial operations. A typical process control system includes one or more process controllers communicatively coupled to each other, to at least one host or operator workstation, and to one or more field devices via analog, digital or combined analog/digital buses. Process facility management providers develop such process control systems to satisfy a wide range of process requirements and facility types. A primary objective of such providers is to control, in a centralized or decentralized system, as many processes as possible to improve the overall efficiency of the facility. Each process, or group of associated processes, possesses certain input (e.g., flow, feed, power, etc) and output (e.g., temperature, pressure, etc) characteristics.
A common approach to advanced industrial process control involves the use of MPC (Model-based Predictive Control) techniques. MPC is a control strategy that utilizes an optimizer to solve for a control trajectory over a future time horizon based on a dynamic model of the process. In the majority of prior art MPC approaches, the current measured disturbance remains constant over the entire prediction horizon because there is no process information in the future. Such a feature may be referred to as a constant additive disturbance assumption. In many, if not most, applications, this adversely affects the regulatory performance of a standard MPC controller. Also, for high-frequency/pulse disturbances, such an approach results in an oscillatory behavior of unforced predictions and significant control effort.
Based on the foregoing, it is believed that a need exists for an improved method and system for predicting future disturbances in an MPC application. Such an improved method and system is described in greater detail herein.